Study On Preparation And Properties Of Graphene Thermal Conductive Nanocomposite

In this study,the functionalization of two kinds of liquid crystal molecules-biphenyl type liquid crystal,4-allyl-4'-hydroxy biphenyl(AOBPO)and 4-allyl-4'-allyl biphenyl(DABP)were carried out,and two kinds of liquid crystal functionalized three different kinds of graphene(GO,r GO,GNS(High Temperature Reduction)).The morphology,structure and the interaction between liquid crystal and graphene were characterized by scanning electron microscopy,X-ray diffraction,infrared spectroscopy,fluorescence spectroscopy and thermal analysis of polarized light microscopy.And GO-AOBPO,r GO-AOBPO,GNS-AOBPO,GO-DABP,r GO-DABP and GNS-DABP were used to fill epoxy resin to prepare graphene thermally conductive nanocomposites,and the using of graphene coated copper nanoparticles,aluminum nitride,boron nitride materials as fillers to prepare graphene coated copper nanoparticles/aluminum nitride /boron nitride thermal conductive composite materials and study the thermal conductivity of these materials.The FT-IR spectrum shows that GO-AOBPO forms an ester group,and only GO-AOBPO is covalently bonded.The fluorescence spectra show that there is ?-? conjugation between GO?r GO?GNS and AOBPO,both DABP.The XRD characterization of the materials showed that the interlayer spacing of the GO-AOBPO composites was 0.34 nm.The TGA curve shows the functional modification of the three different kinds of graphene by liquid crystal.The thermal conductivity of the composites showed that the thermal conductivity of the two kinds of liquid crystal modified graphene materials was used as the filler,and the thermal conductivity was improved compared with the unmodified filler.The thermal conductivity of the composites is greatly improved by applying the shear force field to the orientation of graphene.The conductivity of the composites also increases with increasing filler content.The conductivity of the material is also improved when the shear force field is applied.Graphene oxide as filler composite material is insulated.The thermal conductivity of GNS-AOBPO with 9 wt% filler is increased to 1.161 W/(m?K)after applying the shear force field,the thermal conductivity of GNS-DABP with 9 wt% filler is improved to 1.256 W/(m?K).The thermal conductivities of graphene coated copper nanoparticles/aluminum nitride composites reached 3.908 W/(m?K)when the mass fraction of graphene coated copper nanoparticles was 23 wt%.And the thermal conductivities of graphene coated copper nanoparticles/ boron nitride composites reached 3.811 W/(m?K)when the mass fraction of graphene coated copper nanoparticles was 10 wt%.These two thermal conductive composites have a high thermal conductivity while still maintaining excellent insulation properties.